The present invention relates to a method for qualifying a local loop for digital subscriber line (DSL) service.
xDSL is a generic term for digital subscriber line equipment and services, including packet-based architectures, such as ADSL, HDSL, SDSL, VDSL, and RADSL. That is, x is the generic. DSL technologies provide extremely high bandwidth over embedded twisted pair, copper cable plant. DSL technologies offer great potential for bandwidth-intensive applications, such as Internet access, remote LAN access, video conferencing, and video-on-demand.
ADSL or asymmetric digital subscriber line services generally use existing unshielded twisted pair (UTP) copper wires from the telephone company""s central office to the subscriber""s premise, utilize electronic equipment in the form of ADSL modems at both the central office and the subscriber""s premise, send high-speed digital signals up and down those copper wires, and send more information one way than the other. The ADSL flavor of DSL services is capable of providing a downstream bandwidth of about 1.5 Mbps-6.144 Mbps, and an upstream bandwidth of about 32 Kbps-640 Kbps with loop distances ranging from about 3.7 km-5.5 km. HDSL or high bit rate digital subscriber line services provide a symmetric, high-performance connection over a shorter loop, and typically require two or three copper twisted pairs. HDSL is capable of providing both upstream and downstream bandwidth of about 1.5 Mbps, over loop distances of up to about 3.7 km. SDSL or single line digital subscriber line services provide a symmetric connection that matches HDSL performance using a single twisted pair, but operating over a shorter loop of up to about 3.0 km. VDSL or very high bit rate digital subscriber line services are typically implemented in asymmetric form, as a very high speed variation on the ADSL theme over a very short loop. Specifically, target downstream performance is typically about 52 Mbps over UTP local loops of 300 m, 26 Mbps at 1,000 m, and 13 Mbps at 1,500 m. Upstream data rates in asymmetric implementations tend to range from about 1.6 Mbps to about 2.3 Mbps. Additionally, there is RADSL or rate adaptive digital subscriber line services. RADSL provides a dynamic connection that adapts to the length and quality of the line.
In the DSL family of services, many DSL themes, including ADSL, HDSL, SDSL, VDSL, and RADSL, utilize a packet-based approach that does away with the line-grabbing practice of circuit switched networks, such as ISDN (although ISDN service is a form of digital subscriber line). This packet-based approach is very advantageous in a variety of situations, such as high-speed data services, including high definition television or HDTV transmissions.
Of course, DSL services, also commonly referred to as simply DSL or digital subscriber line services, are much more dependent on line conditions than traditional telephone services. Traditional telephone services typically use a bandwidth including frequencies up to about 3 kilohertz, while the DSL services utilize a bandwidth including frequencies up into the hundreds of kilohertz. While some local loops are in great condition for implementing DSL services, that is, the local loops have short to moderate lengths with minimal bridged taps and splices, many local loops are not as clean. For example, local loop length vary widely, for example, from as short as a few hundred meters to as long as several kilometers.
Further, sometimes the wire gauge for a local loop is not continuous over the length of the loop. That is, a portion of the local loop may be one wire gauge, while an adjacent portion of the local loop has a different wire gauge, with the two portions being spliced together. Still further, many existing local loops have one or more bridged taps. A bridged tap is a length of wire pair that is connected to a loop at one end and is unterminated at the other end. Sometimes, an existing local loop will have several bridged taps so that the telephone company may connect a customer to any one of the taps (while leaving the other taps unterminated). Tapped lines may allow the telephone company to better utilize its copper cable plant distribution. For example, a particular service area may include 25 residences. Because not all residences require multiple phone lines, there may be a total of about 30 or 35 local loops, with some of the loops having multiple bridged taps. As such, it may be possible for any one of the residences to order multiple line service, so long as only a few of the residences do so.
Because so many different factors affect the success of a DSL solution, the question of whether or not a particular local loop qualifies for any level of DSL service is a complicated one. Due to varying line conditions, some loops may qualify for the highest quality DSL service, while other loops only qualify for a very limited bandwidth, and still, some of the loops do not qualify at all for DSL service. The steps involved in determining the quality of DSL service that is available on a particular loop is called the loop qualification process. In an existing loop qualification process, a customer calls a DSL service provider and inquires as to the availability of DSL service. The customer service representative then performs a database look-up on the customer""s line and evaluates the ability to receive DSL service. If the customer service representative believes that further inquiry is required, he/she may test the circuit with voice band measurement devices.
Unfortunately, the accuracy of some database records is questionable, and voice band measurements do not always accurately reflect the ability of a loop to support DSL services. As such, many times the customer cannot know the actual available bandwidth for DSL services until after customer premise equipment has been purchased and installed at the customer residence. If, after several steps have been taken to implement a DSL solution, it is then determined that the local loop is in such poor condition that DSL cannot be supported or that the local loop does not support as much bandwidth as the customer anticipated, there can be a lot of disappointment for both the customer and the service provider.
For the foregoing reasons, there is a need for a method that allows a customer to determine whether or not a local loop is capable of receiving DSL service that overcomes the limitations associated with the prior art.
It is, therefore, an object of the present invention to provide a method for qualifying a local loop for digital subscriber line service that transmits a test signal from the customer end of the loop and measures the reflected signals to qualify the loop.
In carrying out the above object, a method for qualifying a local loop for digital subscriber line service is provided. The loop has a provider end at a local switch and a customer end with a computer connected to the customer end. The computer includes a modem providing the connection to the loop. The method comprises initiating a loop qualification test at the computer. The method further comprises communicating with the modem to transmit a set of signals over the loop, and communicating with the modem to receive a set of reflected signals. The reflected signals correspond to the transmitted signals as reflected at the local switch. Further, a test result is determined for the loop qualification test based on the set of reflected signals.
Preferably, the computer executes software including a modem device driver. Communicating with the modem to transmit and to receive are performed with the modem device driver. In some embodiments, determining the test result further comprises determining a signal to noise ratio for a reflected signal of the set of reflected signals. In some embodiments, determining the test result further comprises determining a return loss for a reflected signal of the set of reflected signals. As appropriate, a substantially matching impedance may be provided at the modem to reduce the modem reflection coefficient. In some embodiments, initiating the loop qualification test at the computer further comprises executing a miniprogram on the computer. The miniprogram, in some embodiments, is in a browser executable format.
Further, in carrying out the present invention, a method for qualifying a local loop for digital subscriber line service is provided. The loop has a provider end and a customer end with a computer connected to the customer end. The computer includes a modem providing the connection to the loop. The method comprises establishing a connection to a test server with the modem, and downloading a computer program from the test server. The method further comprises executing the computer program to initiate a loop qualification test at the computer. The computer program directs the computer to terminate the server connection, and transmit a set of signals over the loop. The computer program further directs the computer to receive a set of reflected signals corresponding to the transmitted signals, and to determine a test result for the loop qualification test based on the set of reflected signals.
Preferably, the computer program further directs the computer to re-establish a connection to the test server, and to send the test result to the test server. The test server interprets the test result and reports the interpreted result. In some embodiments, determining the test result further comprises determining a signal to noise ratio for a reflected signal of the set of reflected signals. In some embodiments, determining the test result further comprises determining a return loss for a reflected signal of the set of reflected signals. In some embodiments, a substantially matching impedance is provided at the modem to reduce the reflection coefficient at the modem. In some embodiments, the computer program has a browser executable format such as JAVA or ACTIVEX. In other embodiments, the computer program may be an operating system executable file.
Still further, in carrying out the present invention, a computer readable storage medium is provided. The computer readable storage medium includes instructions represented by information stored on the medium. The instructions are executable to perform a method for qualifying a local loop for digital subscriber line service. The loop has a provider end at a local switch and a customer end with a computer connected to the customer end. The computer includes a modem providing the connection to the loop. The computer readable storage medium further comprises instructions for initiating a loop qualification test at the computer, instructions for communicating with the modem to transmit a set of signals over the loop, and instructions for communicating with the modem to receive a set of reflected signals. The reflected signals correspond to the transmitted signals as reflected at the local switch. The computer readable storage medium further comprises instructions for determining a test result for the loop qualification test based on the set of reflected signals.
In some embodiments, the instructions are in a browser executable format. In some embodiments, the instructions are in a virtual machine executable format. In some embodiments, the instructions are in an operating system executable format.
The advantages associated with embodiments of the present invention are numerous. For example, embodiments of the present invention perform a loop qualification initiated by the customer side. Advantageously, embodiments of the present invention may be achieved using a 56 kbps modem (having the appropriate transmitting and receiving capabilities) or DSL modem having appropriate hardware capabilities and an appropriate device driver. In accordance with the present invention, the customer may initiate a loop qualification test and obtain a test result for the local loop. Depending upon the local loop and the termination in the central office, the measure of returned frequency and decibel (dB) value would help determine the line""s ability to support DSL service. It is appreciated that embodiments of the present invention may take the form of a computer program. In some implementations, the computer program may be a miniprogram such as a JAVA applet or ACTIVEX program that may be downloaded over the Internet and then executed at the customer side. In the alternative, the computer program may be a stand-alone executable, possibly distributed on CD ROM.